What is the y-intercept in the equation y=-2x + 5

Ineed with number 17 i don’t get it at alll

If 30 lb of rice and 30 lb of potatoes cost ? $27.60? , and 20 lb of rice and 12 lb of potatoes cost ? $15.04? , how much will 10 lb of rice and 50 lb of potatoes? cost?

If t17 = 3 (t5) in an arithmetic progression, find t1 in terms of d.