Answer:
180
Step-by-step explanation:
60 * 4 = 240
240 / 20 = 12 groups of 20
12*15 = 180
180 cookies
She simplified it wrong because you're only supposed to simplify it with the same numbers. For example: simplify 2/4. You divide it by 2/2. You do the same and it will be correct.
15-t + 8t = -13
15 + 7t = -13
7t = -13-15
7t = -28
t = -4
4a + 11-a = 2
3a = 2-11
3a = -9
a = -3
