Radio tower had a special on rechargeable batteries. it sold aa for $1 and aaa for $0.75. it sold 42 batteries on a single day and received $37. how many batteries and which type were sold ?

AA = $1
AAA= $0.75

AA + AAA = 42

$1AA + $0.75AAA= $37

AA + AAA = 42
AA + AAA-AAA= 42- AAA
AA = 42- AAA

$1(42- AAA) + $0.75AAA= $37
$42 - AAA +0.75AAA = $37
$42 -0.25AAA= $37
$42-$42 -0.25AAA= $37 -$42
-0.25AAA= -5
-0.25AAA/-0.25 = -5/-0.25
AAA= 20

AA + AAA= 42
AA + 20 = 42
AA +20 -20 = 42-20
AA= 22

Check
$1AA + $0.75AAA= $37
$1(22)+ $0.75(20)= $37
$22 + $15 =$37
$37 = $37