Answer
See the explanation
Work Step by Step
From the previous task, solution is $(40,15,30)$. Let's check the solution by substituting in each equation:
$$25x+40y+20z=2200$$
$$25(40)+40(15)+20(30)=1000+600+600=2200$$
First is correct.
$$4x+2y+3z=280$$
$$4(40)+2(15)+3(30)=160+30+90=280$$
Second is correct.
$$3x+2y+1z=180$$
$$3(40)+2(15)+1(30)=120+30+30=180$$
Third is correct.