Answer:
7 shirts
Step-by-step explanation:
You first have to subtract 22 from 80, since that's how much she already spent, 80-22=58. Now you have to do 58/8, but since 8 doesn't divide evenly into 58, you have to go with the closet multiple of 8 which would be 56. 7x8=56, so Jenna can buy a maximum number of 7 shirts.
Notice that
13 - 9 = 4
17 - 13 = 4
so it's likely that each pair of consecutive terms in the sum differ by 4. This means the last term, 149, is equal to 9 plus some multiple of 4 :
149 = 9 + 4k
140 = 4k
k = 140/4
k = 35
This tells you there are 35 + 1 = 36 terms in the sum (since the first term is 9 plus 0 times 4, and the last term is 9 plus 35 times 4). Among the given options, only the first choice contains the same amount of terms.
Put another way, we have
but if we make the sum start at k = 1, we need to replace every instance of k with k - 1, and accordingly adjust the upper limit in the sum.
Answer:
85 ° is the answer to the question