Ricardo's employer pays 90% of the total cost of his family's health insurance plan, while Ricardo pays the rest. If the total cost of the plan will increase from each per month to $700 per month, how much more will Ricardo have to pay month?
Ricardo's employer pays 90% of his family's health insurance. So Ricardo pays 10%.
The plan increases by $700/month - how much more does Ricardo pay?
We know that he pays 10%, so he'll pay 10% of the increase. So we can write: