How do I solve 12x+7y=3100 without guessing and checking

Is 3/7 bigger. Or 2/3 bigger

The expression 15n + 12n + 100 rersents the total cost in dollars for skis, boots and a lesson for n skiers. simplify the expression 15n + 12n + 100, then find the total cost for 8 skiers.

A certain brand of coffee comes in two sizes. An 11.3 - ounce package costs $2.88. A 27.8 - ounce package costs $6.48. Find the unit price for each size. Then state which size is the better buy based on the unit price.

A sack contains red and blue marbles. the ratio of red marbles to blue marbles is 4:3. if there are 16 red marbles in the sack, how many blue marbles are in the sack?

Which of the expressions results in a product greater than 45? a. 4/5x45 b. 45. 4.5 C. 45 x 5/4 D. (0.45) 45

There's 7/12 you get 1/7 how much is left

50% of all cakes were party cakes 1/5 fruit cakes the remainder sponge cakes what percentage of sponge cakes were made

Three-tenths of the total volume, v, of water in a bucket spills. Which statement explains why 3/10x and 0.3x can each find the volume of the water that spilled? The fraction 310 is equivalent to the decimal 0.03.

A rectangle has side lengths of 5 centimeters and 3 centimeters. If the side lengths are doubled, will the area also double?

It takes three bananas to make 5 loaves of banana bread. How many bananas are needed to make 42 loaves? If necessary, round to the nearest banana.