She already had $37 but she deposits $150. Deposit means to put more money in. So, add $150 to $37.
$150 + $37 = $187
But, now she writes a check for $61, so that deducts $61 of her account. So subtract $61 from $187.
$187 - $61 = $126
She has $126 in her checking account now.
Hope this helps! Have a happy thanksgiving, here's a turkey.