A ruler cost Y kobo, an eraser is 5 kobo less than thrice the ruler.Find the cost if the ruler and eraser.

r = Y

e = 3 r - 5
or
e = 3 Y - 5
You better know Y

Ruler cost Y kobo.

Eraser cost 3y - 5 kobo.
Total cost = y + 3y-5 = 4y-5.

To find the cost of the ruler and eraser, let's first represent the cost of the ruler using a variable. Let's call it "X" kobo.

Given that the ruler costs Y kobo, we can set up the equation:

X = Y

Next, we are told that the eraser is 5 kobo less than thrice the cost of the ruler. "Thrice the ruler" means three times the cost of the ruler, so we can represent the cost of the eraser as:

Eraser cost = 3X - 5

Now, we can substitute the value of X from the first equation into the second equation to get the cost of the eraser:

Eraser cost = 3(Y) - 5

Therefore, the cost of the ruler and eraser is:

Ruler cost (X) = Y kobo
Eraser cost = 3(Y) - 5 kobo