A = 8, B = 9

A is 8 be is 9

A:8 and b : 9. Both a+a must give 16 with 1 carried over from b+b. B+b must be a number ending with 8 so only 4+4 and 9+9 are the only possibilities but 4+4 not possible because b+b must be a double digit so that 1 in the tens place can be carried over to a+a to get 17

Two numbers added together to male 170 is 85. So the A-8. Then to make 8 and add the one to the tens you need to add 4 more making B 9

Thanks to all. Is there any model to solve this?

This one doesn't need model

It's by reasoning

Tnx

Hi you can look at this model at q39. which is for this question. Sorry I can't remember the actual explanation from my father in law. Hope someone can explain later

Thanks but I don't understand how 12 +1u is derived :(

If I never rem wrong because it's age so the person will still grow every year.

Amir = 5u Eric = 12u Eric has 7u more than Amir 1/2 of 7u = 35 1u = 35 x2/7 = 10 Amir = 5 x 10= 50

I did with 2 methods. Either one can be used.

Thank you all . I love this FB group !

From the first sentence, "Amir had 5/12 as many coins as Eric.", we can find out that Amir had 5 units while Eric had 12 units. However, odd number is not able to give whole number when divided by 2. Hence, I've multiplied both units by 2.

Thanks Adrian

what are the identities you used?

Definitely not psle. Pri sch olympiad?

Wrong group lah. Please join us at "Singapore secondary and JC mathematics" Don't scare the little ones here

lolz....oh come on..lolz

Easy lah..this one is under trigo in A math..wrong group liao

oh sorry

Aaron u can post here: Homework Helper/Solver

Using rhs to prove lhs

Just one. cos 2x = 2(cos x)^2 - 1

alright,,thanks..

by the way how does cos4x became (2cos^2)(2x) -1

Same. Just replace x <-> 2x

ok,,

what if you wanna solve the RHS?

You can't "solve" the RHS. Give me an equation.

the same equation

This isn't an equation. It's an identity... hello...

i mean identity* sorry

You can't solve an identity. It's valid for every value of x. What's there to solve?

what if you wnna prove that 8(cosx)^4-8(cosx)^2-1= cos4x is it the same process to the way you solve it earlier?

Yes. Rewrite my steps from bottom to top

ok...thanks