, 2013

Since the regular price for the bicycle is $320 and the savings are 20%, then the amount of money that Sandra saves on the bicycle is $\$320 \times 20\% = \$320 \times 0.2 = \$64$.

Since the regular price for the helmet is $80 and the savings are 10%, then the amount of money that Sandra saves on the helmet is $\$80 \times 10\% = \$80 \times 0.1 = \$8$.

The total of the original prices for the bicycle and helmet is $\$320+\$80 = \$400$.

Sandra’s total savings are $\$64+\$8 = \$72$.

Therefore, her total percentage savings is $\dfrac{\$72}{\$400}\times 100\% = \dfrac{72}{4}\times 1\% = 18\%$.