Answer:
You'd have to buy 3 shirts in order to use your coupon.
Step-by-step explanation:
Each shirt originally costs $17.99
One particular brand of shirts is on sale for 20% off the original price.
$17.99*0.2= $3.60 (amount taken off for each shirt)
Now subtract $3.60 from $17.99.
$17.99 - $3.60 = $14.39 (per shirt)
40 / 14.39 = 2.779 (round to 3)
You'd have to buy 3 shirts in order to use your coupon.
$14.39 * 3 = $43.17, in order to get $10 off you'd need to spend at least $40