#### Answer

Mum's

#### Work Step by Step

You could compute the price per rose in order to find who has the lower cost. However, the solution does not require you to find the actual price per rose. You can more quickly compare prices by computing how much First Flowers would charge for 2 dozen roses. 2 dozen is 24, so multiply the price that First Flowers charges for 6 roses by 4, and then compare the cost of 24 roses at each florist.
$7.50\times4=30$
At First Florist, 24 roses would cost \$30, but at Mum's, they would only cost \$24.60, so Mum's has the lower cost per rose.