Answer:
x = 12
Step-by-step explanation:
If Mary spent $45 altogether,
then she bought lunch for $9
so our equation now is
$45 = $9 + 3x
It is 3x because he bought 3 shirts and we used x because we didnt
now how much the price of those shirts were
$45 = $9 +3x
$45 - $9 = 3x
$45 - $9 = $36
$36 = 3x
$36 / 3 = 12
x = 12
Please mark this answer as the brainliest