Correct Answer - Option 1 : ÷ and -
Given Equation: 570 × 8 - 240 + 75 ÷ 15 = 79
CONCEPT:
Follow BODMAS rule to solve this question by putting combination of signs given in each option, as per the order given below,
Step - 1 - Parts of an equation enclosed in 'Brackets' must be solved first,
Step - 2 - Any mathematical 'Of' or 'Exponent' should be solved next,
Step - 3 - Then, the parts of the equation containing 'Division' and 'Multiplication' operations are solved,
Step - 4 - And lastly, the parts of the equation that contains 'Addition' and 'Subtraction' should be calculated.
So, on using BODMAS and solving each option,
Option1: ÷ and -
On interchanging these signs, the given equation becomes- 570 × 8 ÷ 240 + 75 - 15 = 79
Solving LHS of the equation,
570 × 8 ÷ 240 + 75 - 15
= 570 × 1/30 + 75 - 15
= 19 + 75 - 15
= 94 - 15
=79 = 79, This satisfies the equation.
Option2. + and -
On interchanging these signs, the given equation becomes- 570 × 8 + 240 - 75 ÷ 15 = 79
Solving LHS of the equation,
570 × 8 + 240 - 75 ÷ 15
= 570 × 8 + 240 - 5
= 4560 + 240 - 5
= 4800 - 5
= 4795 ≠ 79 , This does not satisfy the equation.
Option3. + and ×
On interchanging these signs, the given equation becomes- 570 + 8 - 240 × 75 ÷ 15 = 79
Solving LHS of the equation,
570 + 8 - 240 × 75 ÷ 15
= 570 + 8 - 240 × 5
= 570 + 8 - 1200
= 578 - 1200
= - 622 ≠ 79, This does not satisfy the equation.
Option4. × and ÷
On interchanging these signs, the given equation becomes- 570 ÷ 8 - 240 + 75 × 15 = 79
Solving LHS of the equation,
570 ÷ 8 - 240 + 75 × 15
= 71.25 - 240 + 75 × 15
= 71.25 - 240 + 1125
= 1196.25 - 240
= 956.25 ≠ 79, This does not satisfy the equation.
Hence, ÷ and - should be interchanged to make the given equation correct.
