Resposta :
Explicação passo a passo:
saldo credor >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>+ 900,00
compra sapato >>>>>>>>>>>>>>>>>>>>>>>> - 450,00
depósito >>>>>>>>>>>>>>>>>>>>>>>>>>>>> + 320,00
idem >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> + 170,00
cheque celular >>>>>>>>>>>>>>>>>>>>>>> - 1 800,00
SALDO DEVEDOR >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - 860,00
CÁLCULO DO SALDO FINAL
1 =soma tudo que tem sinal IGUAL e conserva o sinal
+900 + 320 + 170 = + 1 390,00
-450 - 1800 = - 2 250,00
2 = Sinais diferentes diminui dá sinal do maior
+ 1 390 - 2 250 =- 860 saldo devedor