$(\,5\,t+\,4)\;(\,3\,x+\,5) = $   ?

$\,8\,\,t\,x +\,10\,\,t +\,7\,\,x +\,9$ $\,15\,\,t\,x +\,25\,\,t +\,12\,\,x +\,20$ $\,52\,\,t^2\,x^2 +\,20$ $\,15\,\,t\,x +\,20$

$(\,2+\,y)\;(\,5+\,y) = $   ?

$\,2\,\,y^2 +\,9\,\,y +\,7$ $\,8\,\,y +\,10$ $\,\,y^2 +\,7\,\,y +\,10$ $\,\,y^2 +\,10$

$(\,x+\,1)\;(\,3+\,4\,y) = $   ?

$\,3\,\,x +\,4\,\,x\,y +\,3 +\,4\,\,y$ $\,4\,\,x +\,5\,\,x\,y +\,4 +\,5\,\,y$ $\,4\,\,x\,y +\,3$ $\,11\,\,x^2\,y^2 +\,3$

$(\,2+\,5\,y)\;(\,1+\,y) = $   ?

$\,12\,\,y +\,2$ $\,5\,\,y^2 +\,2$ $\,5\,\,y^2 +\,7\,\,y +\,2$ $\,6\,\,y^2 +\,9\,\,y +\,3$

$(\,3\,x\,-1)\;(\,5+\,y) = $   ?

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

$(\,5+\,a)\;(\,-\,b\,-4) = $   ?

$\,5\,\,b \,-20 +\,\,a\,b \,-4\,\,a$ $\,5\,\,b \,-20 \,-\,\,a\,b \,-4\,\,a$ $\,-5\,\,b \,-20 \,-\,\,a\,b \,-4\,\,a$ $\,-5\,\,b +\,20 \,-\,\,a\,b +\,4\,\,a$

$(\,6\,a\,-4)\;(\,4\,a+\,6) = $   ?

$\,-24\,\,a^2 \,-52\,\,a \,-24$ $\,-24\,\,a^2 +\,52\,\,a \,-24$ $\,24\,\,a^2 +\,20\,\,a \,-24$ $\,24\,\,a^2 +\,52\,\,a +\,24$

$(\,a\,-6)\;(\,-3\,-\,b) = $   ?

$\,3\,\,a \,-\,\,a\,b \,-18 +\,6\,\,b$ $\,-3\,\,a +\,\,a\,b +\,18 +\,6\,\,b$ $\,-3\,\,a +\,\,a\,b +\,18 \,-6\,\,b$ $\,-3\,\,a \,-\,\,a\,b +\,18 +\,6\,\,b$

$(\,4\,-6\,x)\;(\,-6\,x+\,4) = $   ?

$\,36\,\,x^2 +\,16$ $\,36\,\,x^2 \,-48\,\,x +\,16$ $\,36\,\,x^2 \,-16$ $\,-36\,\,x^2 \,-48\,\,x \,-16$

$(\,x\,-3)\;(\,-6\,-\,x) = $   ?

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