If you are good at math click on this question. I need help on all of them

Some boys and girls were asked if they had a pet. one third of the group were boys. there were 20 boys. 20% of the girls had a pet. boys with a pet : girls with a pet = 1 : 5 i need to know how many girls there are.

Me find the value of x each figure.

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.