Question

A tarifa de ônibus em certo município, era de R$ 3,00 , sofreu dois acréscimos, um de 5% no mês de agosto, e outro de 8% em janeiro do ano seguinte. Qual o valor da tarifa após os aumentos?
a) ( ) R$ 3,10
b) ( ) R$ 3,20
c) ( ) R$ 3,40
d) ( ) R$ 3,50
​

Answer 1

100% + 5%= 105%

Regra de três

100%------> 3,00

105%------> x

100 • x= 105 • 3,00

100x= 315,00

x= 315,00/100

x= 3,15

____________________

100% + 8%= 108%

Regra de três

100%-----> 3,15

108%-----> x

100 • x= 108 • 3,15

100x= 340,2

x= 340,2/100

x= 3,402

Letra C

Answer 2

$\tt 5\% \to \dfrac{5}{100}=0,05\to 0,05+1=1,05 \\\\\\\sf 8\% \to \dfrac{8}{100}=0,08\to 0,05+1=1,08$

$\tt 100x\:=\:3\cdot 5\\\\\\\tt \displaystyle 100x=15\\\\\\\tt \frac{100x}{100}=\frac{15}{100}\\\\\\\boxed{\boxed{\sf x=\frac{3}{20}\to0,15}}\\\\\\\tt 100x\:=\:3,\:15\cdot 8\\\\\\\tt 100x=25.2\\\\\\\tt \frac{100x}{100}=\frac{25.2}{100}\\\\\\\boxed{\boxed{\sf x=0,252}}\\\\\\\\\sf 0,252 + 3,15\to \boxed{\boxed{\sf = 3,40}}$

• c) ( x ) R$ 3,40