Question

Solve :   5a-3(b+c)+145:5-8 if :

3a-2b=b-2a+3c  and  c=[(3+6+9+...+300):303]-40 .

Answer 1

`c=[(3+6+9+...+300):303]-40 \\\\ c=[3(1+2+3+...+100):303]-40 \\\\ c=[3*((1+100)*100)/(2):303]-40 \\\\ c=(3*101*50:303)-40 \\\\ c=(303*50:303)-40 \\\\ c=50-40 \\\\ \boxed{c=10}`
`3a-2b=b-2a+3c \\\\ 3a-2b=b-2a+3*10 \\\\ 3a+2a=b+2b+30 \\\\ 5a=3b+30 \\\\ \boxed{a=(3b+30)/(5)}`


`5a-3(b+c)+145:5-8= \\\\ 5a-3(b+10)+29-8= \\\\ 5*(3b+30)/(5)-3b-30+21= \\\\ =3b+30-3b-30+21= \\\\ =30-30+21= \\\\ =\boxed{\boxed{21}}`