They need at least $1,150
They have already saved $700
They are selling shirts with a profit of $7.00 per shirt
If they sell n number of shirts, they will earn n times $7.00
Since they have already 700, they will earn a total of 700 + 7n
If this quantity has to be equal or grather to 1,150, we can write:
1150 <= 700 + 7n
if we solve this inequality for n:
1150 <= 700 + 7n
1150 - 700 <= 7n
450 <= 7n
450/7 <= n
64.28 <= n
Since th number of shirts has to be an integer (you can not sell "part" of a shirt)
n >= 65
Answer:
n >= 65