To solve this system by substitution, which expression could be substituted for x

Michelle and julie work at a catering company. they need to bake 264 cookies for a birthday party that starts in a little over an hour and a half. each tube of cookie dough claims to make 36 cookies, but michelle eats about 1/5 of every tube and julie makes cookies that are 1.5 times as large as the recommended cookie size.it takes about 8 minutes to bake a container of cookies, but since julie's cookies are larger, they take 12 minutes to bake. a. how many tubes should each girl plan to bake? how long does each girl use the oven? b. explain your solution process what did you make? c. what assumptions did you make?

Julie begins counting backwards from 1000 by 2’s and at the same time tony begins counting forward from 100 by 3’s.   if they count at the same rate, what number will they say at the same time?

4. a single woman uses an online cash flow calculator which reveals a cash flow of 203. what does this mean?