(1) 3x+2y=-1
(2) 6x+4y=0
This system of equation has no solution. Proof
multiply all the term of (1) by two ==>6x+4y=-2
Notice that in (2) you have the same thing but equal to zero.
Same quantity can't equal 0 & -2. So no solution
If it keeps going at the same amount added per week, the two will never reach the same amount.
3 + 0.45*M<=8,40. Notice the equal, because you may use all the money. Then, rearranging: M<=(8.40-3)/0.45= 12, so M<=12. Now, obviously time is positive, so you may end saying 0<=M<=12, with M=0 meaning no call! :)
