maths~f.1升f.2(續)

1.Suppose each kilogram of pork costs $15 and each kilogram of beef costs $21. If Susan uses $140 to buy 8 kilograms of pork and beef altogrther, how many kilograms    of beef does she buy?

2.The number of rotten apples is 3/14 of the total number of apples. If 4 more rotten apples are added, the number of rotten apples will be 1/4 of the total number of apples.How many apples are there originally?

3.Find two consecutive integers such that 3/5 of larger number exceeds 1/4 of the smaller one by 5有2分1.

4.已知一條直線L的線性方程是y=mx+c ,並通過點A(0,-3)及點B(-8,7).
a)求c的值.

b)求m的值.

c)如果直線L通過點D(d,d),求d的值.