At a bake sale brownies were sold for $0.75 each and cookies were sold for $0.50 each there were 10 more coookies sold than brownies and the total amount earned was $40.00 how many brownies and cookies were sold at the bake sale

28 Brownies and 38 Cookies 

Let say the brownies sold for B amount and cookies for C amount. There were 10 more cookies sold than brownies. If brownies sold X piece then, total sales would be:
Sales: (X+10) C + XB

Total sales is $40. Cookies sold for $0.50 each. Brownies sold for $0.75 each. If you insert it all to the first equation, it would become:

$40= (X+10) x $0.50 + $0.75X
$40= $0.50X + $5 + $0.75X
40= 1.25X + 5
1.25X= 35
X= 35 / 1.25= 28

Brownies sold at 28 pieces. Cookies sold at: 26+10= 38 pieces.