Let w = number of weeks.
In week w,
Laura has: 720 + 30w
Taylor has: 1200 - 30w
Set the two amounts equal and solve for w, the number of weeks.
720 + 30w = 1200 - 30w
60w = 480
w = 8
They will have the same amount of money in 8 weeks.
Laura will have in 8 weeks:
720 + 30w = 720 + 30 * 8 = 720 + 240 = 960
Taylor will have in 8 weeks:
1200 - 30w = 1200 - 30 * 8 = 1200 - 240 = 960
They will both have $960 in 8 weeks.
20/28 are female. Since there are 8 male students you just have to subtract 28-8 and you'll get the female total.
