Complete the following tasks for this equation: b/7.8=-2.15

a. give an estimate for the solution. be sure to explain how you arrived at the estimate, either by showing an equation or in words.
b. solve the equation. show or explain your work.
c. compared to your estimate, is your answer reasonable? explain your answer in complete sentences.

Complete the following tasks for this equation: b/7.8=-2.15

a. Give an estimate for the solution. Be sure to explain how you arrived at the estimate, either by showing an equation or in words.

Estimate is b = -17. Since the answer of b divided by 7.8 is -2.15, I know that b should be greater than its double. If we double 7.8 I will get 15.6 so the value should be greater than -15.6 but not so big.

b. Solve the equation. Show or explain your work.

b/7.8 = -2.15, multiply both sides by 7.8 to get

b = (-2.15)*7.8

b= - 16.77

c. Compared to your estimate, is your answer reasonable? Explain your answer in complete sentences.

My estimate is -17 while the computed answer is -16.77. I believe my answer is reasonable since my estimate is just near the computed answer.

See below.

Step-by-step explanation:

b / 7.8 = -2.15

a.  Round 7.8 to 8 and -2.15 to -2, so we have:

    b/8 = -2

    Cross multiply

    b = 8 * -2 = -16 (estimate).

b.  b / 7.8 = -2.15

    Cross multiply:

    b = 7.8 * -2.15 = -16.77.

c.    -16.77 and -16  are quite close (within 5%) so the answer is entirely reasonable.

answer: 1 + 1 = 11

step-by-step explanation:

the surface area is 124cm²

step-by-step explanation:

length: 4cm

width: 9cm

height:   2cm