You have not specified what Gina's medical bills are.

The two plans are equivalent when the bills are

180 + .40(b - 180) = 230 + .25(b - 230) (equate the cost of the plans)

180 + .40b - 72 = 230 + .25b - 57.50 (use the distributive property)

108 + .40b = 172.50 + .25b (collect the constant terms)

.15b + 108 = 172.50 (subtract .25b)

.15b = 64.50 (subtract 108)

b = 430 (divide by .15)

For bills greater than $430, Plan B saves money.

The savings is the difference in cost between the two plans. We assume that Plan B is lower cost for Gina.

savings = 180 + .40(b - 180) - (230 + .25(b - 230))

= 180 + .40b - 72 - (230 + .25b - 57.50)

savings = .15b - 64.50

Example

Gina's bills are $1000.

Her savings under Plan B are .15(1000) - 64.50 = 150 - 64.50 = 85.50.

Under Plan A, she pays 180 + .40(1000-180) = 508.00

Under Plan B, she pays 230 + .25(1000-230) = 422.50

The two plans are equivalent when the bills are

180 + .40(b - 180) = 230 + .25(b - 230) (equate the cost of the plans)

180 + .40b - 72 = 230 + .25b - 57.50 (use the distributive property)

108 + .40b = 172.50 + .25b (collect the constant terms)

.15b + 108 = 172.50 (subtract .25b)

.15b = 64.50 (subtract 108)

b = 430 (divide by .15)

For bills greater than $430, Plan B saves money.

The savings is the difference in cost between the two plans. We assume that Plan B is lower cost for Gina.

savings = 180 + .40(b - 180) - (230 + .25(b - 230))

= 180 + .40b - 72 - (230 + .25b - 57.50)

savings = .15b - 64.50

Example

Gina's bills are $1000.

Her savings under Plan B are .15(1000) - 64.50 = 150 - 64.50 = 85.50.

Under Plan A, she pays 180 + .40(1000-180) = 508.00

Under Plan B, she pays 230 + .25(1000-230) = 422.50