'of' in mathematics means multiplication
'is' in mathematics means equal
Translating 60% of what number is 21 into an equation, we get:
60% * x = 21
60%, or 60 percent, is 60 over 100 which is 60/100. This can be simplified to 3/5.
3/5 * x = 21
Multiply both sides by 5.
3/5 * 5 * x = 21 * 5
3x = 105
Divide 3 on both sides.
3x/3 = 105/3
x = 35
60% of 35 is 21.
