To solve the equation, we need to isolate the term cos(3x - π/4) by itself.

cos(3x - π/4) = 0.7

We know that the cosine function has a range between -1 and 1, so we know that 0.7 is within that range.

Now, we need to find the angle whose cosine is equal to 0.7. This can be done by using the inverse cosine function (cos⁻¹):

3x - π/4 = cos⁻¹(0.7)
3x - π/4 = 0.7954

Now, isolate x:

3x = 0.7954 + π/4
3x = 1.9828

x = 1.9828 / 3
x ≈ 0.6609

Therefore, the solution to the equation cos(3x - π/4) = 0.7 is approximately x = 0.6609.