2a. ten times the sum of 2.5 and 13.5
2a value is 160
2b. the difference of 98 and 78 multiplied by 11
2b value is 220
2c. the sum of 71 and 29 multiplied by 26
2c value is 2600
2d. the product of 50 times 2 added to the product of 15 times 2
2d value 130