The reading in the ideal voltmeter $$V$$ shown in the given circuit diagram is: 

Total cells in the main loop aiding the same current direction:

$$n = 3 \text{ (top)} + 1 \text{ (left)} + 3 \text{ (bottom)} = 7$$

Total loop EMF and resistance:

$$E_{\text{total}} = 7 \times 5 = 35\text{ V}$$

$$r_{\text{total}} = 7 \times 0.2 = 1.4\ \Omega$$

Loop current:

$$I = \frac{E_{\text{total}}}{r_{\text{total}}} = \frac{35}{1.4} = 25\text{ A}$$

Terminal voltage across the rightmost branch cell: $$V = E - Ir \implies V = 5 - (25 \times 0.2) = 0\text{ V}$$