$30 is 60% of $50.
100 % is the whole figure. Based on the problem, 100 % is separated into two parts, 60% and 40%
100% = 60% + 40%
To get the number where $30 is 60%. Let X be the 100% number.
First, divide all number by 100% to remove the percentage and get the whole number.
100%X = 30 + 40%X
X = 30 + 0.40X
X - 0.40X = 30
0.60X = 30
To get X, divide both sides by 0.60
X = 30 / 0.60
X = 50
To check: Substitute all X by 50.
X = 30 + 0.40X
50 = 30 + (0.40*50)
50 = 30 + 20
50 = 50 EQUAL. CORRECT.