Kwan is building a wheelchair ramp onto his porch. If the porch is 60 centimeters high and Kwan wants the ramp to start 63 centimeters from the porch, how long does the ramp need to be?

Kwan is building a wheelchair ramp onto his porch. If the porch is 60 centimeters high and Kwan wants the ramp to start 63 centimeters from the porch, how long does the ramp need to be?