Respuesta :
					                   we take sheritas age as X
3x +4= shandas age
shandas age =3*3+4= 9+4= 13
					                
					             3x +4= shandas age
shandas age =3*3+4= 9+4= 13
					                   If Sherita is 3 years old do 3x (3x3) then you add 4 so your equation is 3x +4. 
					                
					                
					             