$(\,4+\,x)\;(\,y+\,5) = $   ?

$\,5\,\,y +\,9 +\,2\,\,x\,y +\,6\,\,x$ $\,4\,\,y +\,20 +\,\,x\,y +\,5\,\,x$ $\,\,x\,y +\,20$ $\,10\,\,x^2\,y^2 +\,20$

$(\,y+\,3)\;(\,y+\,1) = $   ?

$\,5\,\,y +\,3$ $\,\,y^2 +\,3$ $\,\,y^2 +\,4\,\,y +\,3$ $\,2\,\,y^2 +\,6\,\,y +\,4$

$(\,6+\,b)\;(\,5+\,2\,a) = $   ?

$\,30 +\,12\,\,a +\,5\,\,b +\,2\,\,a\,b$ $\,19\,\,a^2\,b^2 +\,30$ $\,11 +\,8\,\,a +\,6\,\,b +\,3\,\,a\,b$ $\,2\,\,a\,b +\,30$

$(\,5\,b+\,1)\;(\,4+\,3\,b) = $   ?

$\,15\,\,b^2 +\,4$ $\,15\,\,b^2 +\,23\,\,b +\,4$ $\,8\,\,b^2 +\,13\,\,b +\,5$ $\,38\,\,b +\,4$

$(\,4\,t+\,4)\;(\,-3+\,5\,x) = $   ?

$\,12\,\,t +\,20\,\,t\,x \,-12 \,-20\,\,x$ $\,12\,\,t +\,20\,\,t\,x +\,12 +\,20\,\,x$ $\,-12\,\,t \,-20\,\,t\,x +\,12 +\,20\,\,x$ $\,-12\,\,t +\,20\,\,t\,x \,-12 +\,20\,\,x$

$(\,2\,-\,a)\;(\,-5\,b+\,3) = $   ?

$\,-10\,\,b \,-6 \,-5\,\,a\,b \,-3\,\,a$ $\,-10\,\,b +\,6 \,-5\,\,a\,b +\,3\,\,a$ $\,-10\,\,b +\,6 +\,5\,\,a\,b \,-3\,\,a$ $\,-10\,\,b \,-6 +\,5\,\,a\,b +\,3\,\,a$

$(\,1\,-6\,t)\;(\,6+\,t) = $   ?

$\,-6\,\,t^2 \,-35\,\,t \,-6$ $\,6\,\,t^2 \,-35\,\,t +\,6$ $\,-6\,\,t^2 \,-35\,\,t +\,6$ $\,6\,\,t^2 \,-37\,\,t +\,6$

$(\,6\,t\,-4)\;(\,-4\,x\,-3) = $   ?

$\,-24\,\,t\,x \,-18\,\,t +\,16\,\,x \,-12$ $\,24\,\,t\,x +\,18\,\,t +\,16\,\,x +\,12$ $\,-24\,\,t\,x \,-18\,\,t \,-16\,\,x +\,12$ $\,-24\,\,t\,x \,-18\,\,t +\,16\,\,x +\,12$

$(\,1+\,6\,y)\;(\,-2\,-3\,y) = $   ?

$\,-18\,\,y^2 \,-9\,\,y \,-2$ $\,-18\,\,y^2 +\,9\,\,y +\,2$ $\,-18\,\,y^2 \,-15\,\,y \,-2$ $\,18\,\,y^2 \,-15\,\,y \,-2$

$(\,6\,y\,-6)\;(\,-\,y\,-4) = $   ?

$\,6\,\,y^2 +\,30\,\,y +\,24$ $\,-6\,\,y^2 \,-18\,\,y +\,24$ $\,-6\,\,y^2 +\,30\,\,y \,-24$ $\,-6\,\,y^2 \,-30\,\,y +\,24$