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If a quantity A is decreased by 15%, it means that what is left is 85% of it.

85%A=

Part A.

Consider the 150 marigolds.

After the first month, 0.85*150 are left

After the second month, 0.85*0.85*150=

After the third month, 0.85*0.85*0.85*150 =

.

.

so After n months, marigolds are left.

in functional notation: is the function which gives the number of marigolds after n months

consider the 125 sunflowers.

After 1 month, 125-8 are left

After 2 months, 125-8*2 are left

After 3 months, 125-8*3 are left

.

.

After n months, 125-8*n sunflowers are left.

In functional notation: S(n)=125-8*n is the function which gives the number of sunflowers left after n months

Part B.

marigolds are left after 3 months.

S(3)=125-8*3=125-24=121 sunflowers are left after 3 months.

Part C.

Answer : equalizing M(n) to S(n) produces an equation which is very complicated to solve algebraically.

A much better approach is to graph both functions and see where they intersect.

Another approach is by trial, which gives 14 months

which are close numbers to each other.

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