A) Work out the value of 5^2 – 1^5× 2^4
b) Work out the value of 7^2 + 4^3 ÷ 2^5

First you have to know BODMAS/BIDMAS (idk if all schools teach it like this) but this is the order in which you complete questions so it’s Brackets, Indices, Division/Multiplication, Addition/Subtraction
a) 5^2 is 5x5 which equals 25 1 to the power of anything is always 1 and 2^4 is 2x2x2x2 which is 16
So 5^2-1^5x2^4 = 25-1x16 which is then 25-16 = 9
b) 7^2+4^3 divided by 2^5 so 7^2 is 7x7 which = 49 then 4^3 means 4x4x4 = 64 and 2^5 is 2x2x2x2x2 which equals 32 so
7^2+4^3 divides by 2^5 is 49+64/32 = 49+2 which is 51

Maybe the answer is 20mm. all i really did was just multiply, which is obvious.