Question

A dealer buys 120 pens of which x cost R3 each and the rest R4 each an expression in terms of x and the number of the more expensive pens he buys is

Answer 1

Expression in terms of $x$$=480-x$

The number of the more expensive pens he buys$=120-x$

Step-by-step explanation:

Given: Total pen the dealer buys$=120$

Cost of x pens$=3$ Rs each

Cost of remaining pens$= 4$ Rs each

To Find:Expression in terms of $x$ and the number of the more expensive pens he buys is

Concept/Formula used:

Cost of $x$ pens$=3x$

Cost of $(120-x)$ pens$=4(120-x)$

Total cost of $120$ pens expression in terms of $x$$=3x+4(120-x)$

$=3x-4x+480=480-x$

Expression in terms of $x$$=480-x$

Number of more expensive pens he buys(Rs$4$ pens)$=120-x$

Answer 2

Given that No.of pens =120, find expression for total of all pens

Explanation:  

• 3x is the cost of x pens
• 4*(120 - x) is the cost of the remaining pens  
• 3x+4*(120 - x) is the total cost of all 120 pens.