Can you help me on the backsolving question 7 on pg. 37? Its got me stumped even with the backsolving.
Sure! I trust you already looked at the solution in the back, which walks through the backsolve, so maybe I’ll show you the algebra?
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Let’s say is the number of subway trips and
is the number of car trips. She commutes 5 days, so she takes 10 total trips:
. We also know she spends a total of $74.75, so our second equation is
. Solve the system!