Respuesta :
Answer: $ 25
Step-by-step explanation:
Given: The amount of money repaid can be represented using the recursive formula [tex]a_n=50+a_{n-1}[/tex], where n is the number of week.
Since during the fourth week, Johann repaid his parents $175.
Thus, [tex]a_4=50+a_3[/tex]
[tex]\Rightarrow175=50+a_3\\\Rightarrow\ a_3=175-50=125[/tex]
Now, [tex]a_3=50+a_2[/tex]
[tex]\Rightarrow125=50+a_2\\\Rightarrow\ a_2=125-50=75[/tex]
[tex]a_2=50+a_1[/tex]
[tex]\Rightarrow75=50+a_1\\\Rightarrow\ a_1=75-50=25[/tex]
Hence, the total which Johann had repaid after the first week = $ 25