subtract 5 from both sides. -1.6r=-5 divide both sides by-1.6. r=-5/-1.6 simp;ify-5/1.6 to 3.125. r =3.125
Answer: r=8
Step-by-step explanation: -1.6r+5=-7.8
-16/10r+5=-78/10
-2^4/2.5r+5= -2X3X13/5
-2^3/5r+5= - 3X13/5
(-8r)+25/5=-3X13/5
=8 so r=8
