Answer:
$63
Step-by-step explanation:
we know that
Keith bought 4 shirts for $36
so
using proportion
Find out would be the cost for 7 shirts
Let
x ----> the cost for 7 shirts

Correct! lines that have undefined slopes are always parallel to the y-axis as the change in x is 0. A gradient is calculated by the change in y divided by the change in x and anything divided by 0 is referred to as undefined.

(calculation for a gradient)
Hope that helps sorry if its a bit confusing :)
It would be 734.16 because 638.40+15% = 734.16
Answer:
the answer would be 1.474166814×10