SG chevron_right Primary 4 chevron_right Number and Algebra

Can someone help me on this P4 question? Unable to solve it.

SG chevron_right Primary 6 chevron_right Number and Algebra

Anyone can help without using algebra method? Thanks

SG chevron_right Primary 6 chevron_right Number and Algebra

And this. Thanks

SG chevron_right Primary 6 chevron_right Number and Algebra

Anyone can help? Thanks

SG chevron_right Primary 6 chevron_right Number and Algebra

How would you solve this?