To complete this question we can use the FOIL method.
First we can multiply out the First number in each of the brackets - 3x5=15
Then we multiply the Outer numbers in each bracket - 3x-√ 2=-3√ 2
Then the Inner numbers - √ 2x5=5√ 2
And finally the Last number in each bracket - √ 2x-√ 2=-2 as a square root times a square root is just the number.
We then add all our calculations - 15-3√ 2+5√ 2-2= 13+2√ 2