Your mother gave you $13.35 to buy a present. This covered 3/5 of the cost. Write and solve an algebraic equation to find the cost of the present.

The present cost

$22.20

Explanation:

Represent the cost of the present by the variable

c

We are told

XXX

3

5

×

c

=

$

13.32

(this is the requested equation)

Multiplying both sides by

5

3

(to get rid of the fraction on the right side)

XXX

5

3

×

3

5

×

c

=

$

13.32

$

4.44

×

5

3

XXX

→

c

=

$

22.20

hello from mrbilldoesmath!

answer:

a(n) - a(n-1) -3

discussion:

this ones a bit interesting. given a(n) = 5 - 3n consider this:

a(n-1) = 5 - 3(n-1)

          = (5 - 3n) + 3             => but a(n) = 5 - 3n, the first term

          = a(n)   + 3                 => subtract 3 from both sides

a(n-1) -3 = a(n)  

or

a(n) - a(n-1) -3

you,

mrb

step-by-step explanation: