Colour of marbles
Sophie has a box of red, blue, and green marbles. There are 3 times as many red marbles as blue marbles, and 6 fewer green marbles than red marbles.
If Sophie has 43 marbles in total, how many of each colour does she have?
Word Problem
A bridge is built across a river. One quarter of the bridge is over the left bank of the river and one third of the bridge is over the right bank. The river is 120 m wide. How long is the bridge?
Let the number of blue marbles be b.
ReplyDeleteRed marbles = 3b
Green marbles = Red − 6 = 3b − 6
Total marbles:
b + 3b + (3b − 6) = 43
7b − 6 = 43
7b = 49
b = 7
So:
Blue = 7
Red = 3 × 7 = 21
Green = 21 − 6 = 15
Answer: Red 21, Blue 7, Green 15