(71+71+x)/3=76

142+x=228

x=86

2) x= No of months

60*x current cost

.1*60*x=1080

6x=1080

x=180mos or 15 years

(72+80+65+78+60)/5*2/3 + 1/3X = 76. Try it and see

The second one is easy. You are simply going to need to reduce the monthly eating cost by 10%, and divide the cost of the insulation by the result.

so between the 5 other exams the most could have been 66%so add 72,80,65,78,60 and divide by 5 to give an average of 71 in each exam

now multiply 71*0.666666(which is 2/3)

to give 47

76-47= 29

divide by 0.33 to get 87 which is ur answer

10% of 60 is 6

1080/6 is 180 months or 15 years to recover costs( i think)