7 is 10% of yy
nn is 80% of yy
yy is the whole value.
7 and nn are the parts. 10% and 80% are its corresponding percentages.
To get the whole value using part and its corresponding percentage, divide the part by its percentage.
7 ÷ 10% = 70 ← value of yy
Since we already know the whole value, we simply multiply the percentage of the part to get the value of the part.
70 * 80% = 56 ← value of nn
