A cell phone company offers text message plans where the number of texts allowed varies directly with the amount of money paid. Their most popular plan is 400 texts for $8. How many text messages are included in the plan that costs $10? 500, 600, 700, 800
Since the amount of text messages varies directly with the amount of money paid, it will be proportional.
So set up a proportion:
The second plan will be proportional to the first one, so here is the resulting equation:
The number of text messages in the second plan is not known, so I gave it the variable
Now cross multiply to solve:
So the amount of messages included in the second plan is