Question: Math questions (elimination/substitution)?

"Larry's landscaping offers two pay options for employees: 925 per month, plus 25 for every job completed versus \$1000 per month plus \$10 per job completed. Will the pay ever be the same?"

"Hank's Ice Cream Shop sells single and double scoop cones. The single scoop cones cost \$2 and the double scoop \$2.50. In one day he sold 230 cones for a total of \$498 in sales. How many double scoop cones were sold?"

"Plan A for different cell phones plans cost a flat fee of \$22 per month plus .10c per minute of phone usage. Plan B charges 0.18 per min, no flat fee. How many minutes would Nai have to use each month for the cell phones plans to cost the same amount? How much would it cost?

If Naii figures he will talk 400min on the phone each month, which plan should he choose?"

Please answer fast and if you can explain how to do these. We're supposed to use elimination/substitution to solve these and I don't get how. Help..?

Relation questions:

a)
\$925 + \$25job = \$1000 + \$10job
\$15job = \$75
job(s) = 5

b)
\$2x + \$2.50y = \$498
x + y = 230
2(230-y)+2.5y=498
460-2y+2.5y=498
.5y = 38
y = 76
x= 230 - 76 = 154

c)
\$22 + \$.001min = \$.18min
22 = .179min
min = 122.905
cost =122.905*.18 = \$22.13

d)
400 * .18 = \$72
400 * .001 + 22= \$22.4 <- this one is cheaper

hope this helps =)