Given:
Mary spent 30% of her budget in groceries.
She spent 42$ on groceries.
To find:
The total amount of her budget.
Solution:
Let x be the total amount of the budget.
Then, the amount spent on groceries is 30% of x.
[tex]\dfrac{30}{100}x=0.3x[/tex]
She spent 42$ on groceries.
[tex]0.3x=42[/tex]
Divide both sides by 0.3.
[tex]x=\dfrac{42}{0.3}[/tex]
[tex]x=140[/tex]
Therefore, the total amount of the budget is 140$.