#### Answer

20: 144 bpm
50: 120 bpm

#### Work Step by Step

$0.8(200-y)\longrightarrow$ multiply using the distributive property
=$0.8(200)-0.8y\longrightarrow$ simplify
=$160-0.8y$
Substitute the age for a 20 year old.
$160-0.8(20)=160-16=144$
Substitute the age for a 50 year old.
$160-0.8(50)=160-40=120$