Question

In a garden, there are 5 more marigold plants than twice the number of rose plants. There are 15 marigold plants in the garden. How many rose plants are there?
A. 15
B. 3
C. 5
D. None of these

Answer 1

Hint: Here we assume the number of rose plants as a variable and form a relation between number of rose plants and number of marigold plants in one variable (number of rose plants assumed).
* If the first quantity is more than the second quantity by any value \[p\], then the first quantity becomes equal to the second quantity when \[p\]is added to the second quantity. Example: \[m\] is \[7\] more than \[n\] will give us \[m = n + 7\].
* Twice of any number means it is multiplied by \[2\].

Complete step by step solution:
Let us denote number of rose plants by \[x\]
Given there are \[5\] more marigold plants than twice the number of rose plants.
Therefore, number of marigold plants will be two times the number of rose plants plus \[5\]
Number of marigold plants \[ = (2x) + 5\] \[...(i)\]
Given, total number of marigold plants in the garden is \[15\]
Therefore equating equation \[(i)\] and the value \[15\]
\[(2x) + 5 = 15\]

Shifting the constant terms to one side.
\[2x = 15 - 5\]
\[2x = 10\]
Dividing both sides of the equation by \[2\].
\[\dfrac{{2x}}{2} = \dfrac{{10}}{2}\]
\[x = 5\]

Therefore, number of rose plants in the garden is \[5\]

Note:
Students can always check their answer by comparing the total number of marigold plants as the number of marigold plants is more than the number of rose plants.
Students are likely to get confused while adding and subtracting the more and less values respectively. Always add or subtract to the quantity that comes after the word ‘more than’ or ‘less than’ and equate it to the term that is written ‘more than’ or ‘less than’. Example: number of rows is \[3\] more than number of columns. Therefore, we take number of rows on LHS of the equation and add \[3\] to number of columns on RHS of the equation, i.e. number of rows \[ = 3 + \] number of columns