Respuesta :

p + r = 2.50
r = p + 1

p + p + 1 = 2.50
2p + 1 = 2.50
2p = 2.50 - 1
2p = 1.50
p = 1.50/2
p = 0.75 <=== pencil cost 75 cents

r = p + 1
r = 0.75 + 1
r = 1.75 .....ruler cost 1.75
1.75 should be correct by basics of mathematics