21. Carol scored 40 points higher on the math portion of the SAT test than on the language portion. If her total score for both parts was 1260, what was her score on each part?
And in language,
22. How many pounds of cashews selling at $4.00 per pound should be mixed with 3 pounds of peanuts selling at $1.60 per pound to make a mixture selling for $2.80 per pound?
23. The cost C for hiring a bulldozer and its operator is given by C=90h+150, where h is the number of hours that the bulldozer is hired. If the total cost is $510, for how many hours was the bulldozer hired?
Total cost is $510 find the number of hours,