Proportionality · TEKS 7.4D

Percent problems

Percent means "per 100". Most percent problems are one or two multiplications.

Key steps

Percent of a number: change % to a decimal and multiply (25% of 80 = 0.25 × 80).
Discount: price × (1 − rate). Markup or tax: price × (1 + rate).
Percent change = change ÷ ORIGINAL × 100.
Working backwards: sale price ÷ (1 − rate) = original.

Worked example

A $60 jacket is 25% off, then 8.25% tax is added. Total?

Watch out: Percent change always divides by the ORIGINAL amount. Going from $200 to $250 is a 25% increase, not 20%.

Practice

5 questions with new numbers every set. Get 4 of 5 to mark this topic as practiced.