After 10 weeks, the boys will have same amount in savings.
Step-by-step explanation:
Given,
Roberto already have $30.
Amount saved each week = $5
Let,
x be the number of weeks.
R(x) = 30+5x
Amount saved by Jack each week = $8
J(x) = 8x
For same amount, the functions will be equal.
R(x) = J(x)

Dividing both sides by 3

After 10 weeks, the boys will have same amount in savings.
Keywords: functions, division
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2v=3-7
2v=-4 divide both sides
v=-2
240
/ \
5 48
/ \
6 8
/ \ / \
3 2 4 2
The probability of choosing two yellow marbles = 5/26
Step-by-step explanation:
Step 1 :
Given
Total number of marbles in the bag = 13 marbles
Number of yellow marbles = 6.
We choose 2 marbles from the bag without replacing and need to determine the probability that both are yellow.
Step 2 :
Probability of finding yellow marble in the first try = Number of yellow marbles / Total number of marbles = 
Once the yellow marble is selected we have 5 yellow marbles among 12 remaining marbles in the bag.
Probability of finding yellow marble in the second try = Number of yellow marbles / Total number of marbles = 
Step 3:
P(yellow in first 2 tries) = P(yellow in first try) * P(yellow in second try)
P(yellow in first 2 tries) =
= 
Step 4:
Answer:
The probability of choosing two yellow marbles = 5/26