I am assuming they are letting you use a calculator. To find the angle of G, you need to use the sin function first and then use the inverse of the sin which is sin^-1
sin = opposite / hypotenuse
sin = 15 / 17
Now insert 15/17 into the function sin()^-1
sin(15/17)^-1 = 61.92 = G = 62 degrees
