Answer:
24%
Explanation:
assign a variable x:
Find the average and solve for x by isolating the variable:
(x+60%)÷2=42%
multiply on both sides, left side cancels, multiply right side
(x+60%)÷2 *2= 42%*2
x+60% = 84%
subtract on both sides, left side cancels, subtract right side
x+60% - 60%=84% - 60%
x=24%