What do they mean in question b, c

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

Solve for x: 5/3 x = 20/21 it's fraction. remember to simplify your fraction

Th perimeter of a rectangular garden is 150 feet. the length is 50 feet longer than the width, w. which equation could be used to calculate the width of the garden? a.) 2w+ 2(w-50) =150 b.) 2w+50 + 2w =150 c.) 2(w+50) + w =150 d.) 2w+ 2(w + 50) = 150 need asap. will give brainliest !