If C denotes '+', D denotes '×', E denotes '÷' and F denotes '−', then which of the following is true?

Which of two signs when interchanged makes the following equation correct? 7 ÷ 8 × 2 − 16 + 2 = 15

If a * b = ab + b - a, what is the value of c such that c * (2 * 5) = 97?

If ÷ means +, - means ÷, x means - and + means x, then the value of ((36x4)-8x4)/(4+8×2+16÷1) is

If a ÷ b means 'a to be added to b' and a × b means 'a to be divided by b', then the value of (14 ÷ 7) ÷ (14 × 7) is

In an examination, a student gets 4 marks for every correct answer, 1 for every unattempted question and 0 for every wrong answer. If there are 30 questions, which of the following total scores is no…