10² - 2 (8) + 11 . Use PEMDAS, which is the order of operation to follow:
P = parenthesis → 10² - 2x8 +11
E = exponent → 100 - 2x8 +11
M = Multiplication → 100 -16 +11
D = Division → NO DIVISION
A = Addition → 111 -16
S = Subtraction → 95 (answer 3)
Apply the same logic for the 2nd exercice and you will find 26 (I don't see the 26 in your answer but I am sure it's 26)
First isolate the group with h in it
minus 2pir^2 from both sides
s-2pir^2=2pirh
divide both sides by 2pir
(s-2pir^2)/(2pir)=h
C= 6.7
A^2 + B^2 = C^2
6^2 + 3^2 = C^2
36+9 = 45
Square root 45 = 6.7
Well to find the missing side you're going to need the other two. Take the one side and multiply by itself. Take the other one and multiply by itself. Add those two products. Then root it. Basically find something that multiplys by itself to get that product