If you are allowed to use a calculator, this question is quite simple
You have to follow the
BODMAS rule in math to choose what Order to complete the equation.
BODMAS = bracket, exponents (powers and roots etc.), division, multiplication, addition and then subtraction.
For the equation (3+0.3+0.7)2
Complete the BRACKETS first
3+0.3+0.7 = 4
Then the formula becomes 42
42 = 4 x 4 = 16