$(\,x+\,4)\;(\,5+\,2\,y) = $   ?

$\,5\,\,x +\,2\,\,x\,y +\,20 +\,8\,\,y$ $\,2\,\,x\,y +\,20$ $\,15\,\,x^2\,y^2 +\,20$ $\,6\,\,x +\,3\,\,x\,y +\,9 +\,6\,\,y$

$(\,x+\,2)\;(\,5\,x+\,3) = $   ?

$\,5\,\,x^2 +\,13\,\,x +\,6$ $\,6\,\,x^2 +\,11\,\,x +\,5$ $\,18\,\,x +\,6$ $\,5\,\,x^2 +\,6$

$(\,t+\,1)\;(\,1+\,x) = $   ?

$\,\,t +\,\,t\,x +\,1 +\,\,x$ $\,3\,\,t^2\,x^2 +\,1$ $\,\,t\,x +\,1$ $\,2\,\,t +\,2\,\,t\,x +\,2 +\,2\,\,x$

$(\,3+\,t)\;(\,4+\,t) = $   ?

$\,\,t^2 +\,7\,\,t +\,12$ $\,2\,\,t^2 +\,9\,\,t +\,7$ $\,8\,\,t +\,12$ $\,\,t^2 +\,12$

$(\,a+\,6)\;(\,2\,b\,-1) = $   ?

$\,2\,\,a\,b \,-\,\,a \,-12\,\,b +\,6$ $\,-2\,\,a\,b \,-\,\,a \,-12\,\,b \,-6$ $\,2\,\,a\,b +\,\,a \,-12\,\,b \,-6$ $\,2\,\,a\,b \,-\,\,a +\,12\,\,b \,-6$

$(\,3\,x\,-5)\;(\,-5+\,y) = $   ?

$\,15\,\,x +\,3\,\,x\,y +\,25 \,-5\,\,y$ $\,-15\,\,x \,-3\,\,x\,y \,-25 \,-5\,\,y$ $\,-15\,\,x +\,3\,\,x\,y +\,25 \,-5\,\,y$ $\,-15\,\,x \,-3\,\,x\,y +\,25 \,-5\,\,y$

$(\,1+\,y)\;(\,2\,y\,-4) = $   ?

$\,2\,\,y^2 +\,2\,\,y \,-4$ $\,2\,\,y^2 \,-2\,\,y \,-4$ $\,2\,\,y^2 +\,6\,\,y \,-4$ $\,2\,\,y^2 \,-6\,\,y +\,4$

$(\,4\,t\,-4)\;(\,-2\,-\,x) = $   ?

$\,-8\,\,t \,-4\,\,t\,x \,-8 +\,4\,\,x$ $\,-8\,\,t +\,4\,\,t\,x +\,8 +\,4\,\,x$ $\,-8\,\,t \,-4\,\,t\,x \,-8 \,-4\,\,x$ $\,-8\,\,t \,-4\,\,t\,x +\,8 +\,4\,\,x$

$(\,2\,-6\,a)\;(\,3\,-\,a) = $   ?

$\,6\,\,a^2 \,-20\,\,a +\,6$ $\,6\,\,a^2 \,-20\,\,a \,-6$ $\,6\,\,a^2 +\,16\,\,a +\,6$ $\,-6\,\,a^2 +\,16\,\,a +\,6$

$(\,3\,-\,a)\;(\,-6\,-\,a) = $   ?

$\,-\,\,a^2 +\,3\,\,a \,-18$ $\,\,a^2 +\,9\,\,a +\,18$ $\,\,a^2 +\,3\,\,a \,-18$ $\,\,a^2 +\,9\,\,a \,-18$