Verbal Reasoning - Mental Ability Questions

In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question?
642 x 6 ÷ 25 + 4 = ?

In the following question, from the given alternative words, select the word which cannot be formed using the letters of the given word.
RECIPROCATE

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

3, 5/3, 1/3, ? , -7/3, -11/3

If 4Δ2 = 60, 7Δ9 = 160 and 8Δ3 = 110, then find the value of 3Δ2 = ?

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

RST, XYZ, DEF, ?

P and Q start cycling from the same point. P cycles 18 km North, then turns to her right and cycles 3 km. Q cycles 9 km East, then turns North and cycles 10 km North, then turns left and cycles 6 km. Where is Q now with respect to the position of P?

From the given alternative words, select the word which cannot be formed using the letters of the given word:

PHOTOSYNTHETIC

In a certain code language, '+' represents 'x', '-' represents '+', 'x' represents '÷' and '÷' represents '-'. What is the answer to the following question?

12 x 6 ÷ 5 + 4 = ?