The answer would be 48 √6
So r+c=42
c=4+r
subsitute c=4+r for r in r+c=42
r+4+r=42
add like terms
2r+4=42
subtract 4 from both sides
2r=38
divide both sides by 2
r=19
rob=19
subsitute r=19 for r in c=4+r
c=19+4
carly=23
You do 390/100 = 180/x then 390×X=390X
180×100=18000
390X=18000
390X÷390=X
18000÷390=46.15384615=46%
