[tex]\text{Lets find the prices in which they sold their books for}\\\\\text{Katie:}\\\\\text{She sold the book for 25\% less than the original price, so multiply 50 by}\\\text{0.25 and subtract}\\\\50*0.25=12.5\\\\50-12.5=37.50\\\\\text{Becca:}\\\\\text{Becca sold the book for 40\% less than the original price, calculate how}\\\text{much she sold it for}\\\\50*0.40=20\\\\50-20=30\\\\[/tex][tex]\text{We need to find how much more money Katie made than Becca, so subtract}\\\text{Becca's cost from Katie's cost}\\\\37.50-30=7.50\\\\\boxed{\text{Katie received \$7.50 more than Becca}}[/tex]
