cookie = m cents
cake = cookie + 70 = m+70
a)
2 *cake + 4* cookie
= 2* (m+70) + 4*m
= 6m+140
b) m = 80 so cookie = 80 cents and cake = m+70 = 80 + 70 = 150 cents
3 * cake + 2*cookies
3* 150 + 2 * 80 = 610 cents
If Alison is 25 cents short she has 610 - 25 = 585 cents