$(\,4+\,2\,y)\;(\,3+\,5\,x) = $   ?

$\,10\,\,x\,y +\,12$ $\,7 +\,9\,\,x +\,5\,\,y +\,7\,\,x\,y$ $\,36\,\,x^2\,y^2 +\,12$ $\,12 +\,20\,\,x +\,6\,\,y +\,10\,\,x\,y$

$(\,2\,t+\,4)\;(\,t+\,1) = $   ?

$\,8\,\,t +\,4$ $\,2\,\,t^2 +\,4$ $\,2\,\,t^2 +\,6\,\,t +\,4$ $\,3\,\,t^2 +\,8\,\,t +\,5$

$(\,a+\,4)\;(\,2+\,5\,b) = $   ?

$\,5\,\,a\,b +\,8$ $\,27\,\,a^2\,b^2 +\,8$ $\,2\,\,a +\,5\,\,a\,b +\,8 +\,20\,\,b$ $\,3\,\,a +\,6\,\,a\,b +\,6 +\,9\,\,b$

$(\,4\,a+\,4)\;(\,5+\,a) = $   ?

$\,28\,\,a +\,20$ $\,4\,\,a^2 +\,24\,\,a +\,20$ $\,4\,\,a^2 +\,20$ $\,5\,\,a^2 +\,14\,\,a +\,9$

$(\,y\,-4)\;(\,3+\,5\,x) = $   ?

$\,-3\,\,y +\,5\,\,x\,y +\,12 \,-20\,\,x$ $\,3\,\,y +\,5\,\,x\,y \,-12 \,-20\,\,x$ $\,3\,\,y +\,5\,\,x\,y +\,12 +\,20\,\,x$ $\,3\,\,y \,-5\,\,x\,y +\,12 \,-20\,\,x$

$(\,5\,y\,-5)\;(\,4\,-\,x) = $   ?

$\,20\,\,y \,-5\,\,x\,y +\,20 \,-5\,\,x$ $\,-20\,\,y +\,5\,\,x\,y \,-20 +\,5\,\,x$ $\,20\,\,y \,-5\,\,x\,y \,-20 +\,5\,\,x$ $\,20\,\,y +\,5\,\,x\,y \,-20 \,-5\,\,x$

$(\,5+\,6\,a)\;(\,6\,a\,-2) = $   ?

$\,36\,\,a^2 +\,18\,\,a +\,10$ $\,36\,\,a^2 +\,18\,\,a \,-10$ $\,36\,\,a^2 \,-42\,\,a +\,10$ $\,-36\,\,a^2 +\,18\,\,a \,-10$

$(\,a\,-5)\;(\,-3\,-4\,b) = $   ?

$\,-3\,\,a \,-4\,\,a\,b +\,15 +\,20\,\,b$ $\,3\,\,a \,-4\,\,a\,b +\,15 \,-20\,\,b$ $\,-3\,\,a +\,4\,\,a\,b \,-15 +\,20\,\,b$ $\,-3\,\,a +\,4\,\,a\,b +\,15 \,-20\,\,b$

$(\,6\,t\,-1)\;(\,-1+\,t) = $   ?

$\,6\,\,t^2 \,-7\,\,t \,-1$ $\,6\,\,t^2 \,-7\,\,t +\,1$ $\,-6\,\,t^2 \,-7\,\,t +\,1$ $\,6\,\,t^2 +\,7\,\,t +\,1$

$(\,1\,-3\,t)\;(\,-2\,t\,-4) = $   ?

$\,6\,\,t^2 +\,10\,\,t +\,4$ $\,-6\,\,t^2 +\,10\,\,t \,-4$ $\,6\,\,t^2 +\,10\,\,t \,-4$ $\,6\,\,t^2 \,-14\,\,t +\,4$