molar concentration?

Initial moles of AgNO₃ = (1.4 × 10⁻³ mol/L) × (25.0/1000 L) = 3.5 × 10⁻⁵ mol
Initial moles of NaCl = (7.5 × 10⁻⁴ mol/L) × (60.0/1000 L) = 4.5 × 10⁻⁵ mol
Volume of the final solution = (25.0 + 60.0) mL = 85.0 mL = 0.085 L

Precipitation reaction occurs:
AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq)
Mole ratio AgNO₃ : NaCl = 1 : 1

Since (Initial moles of AgNO₃) < (Initial moles of NaCl),
AgNO₃ is the limiting reactant, which completely reacts.
Molar concentration of Ag⁺ ions in the final solution = 0 M

Moles of NaCl unreacted = (4.5 × 10⁻⁵ - 3.5 × 10⁻⁵) mol = 1.0 × 10⁻⁵ mol
[NaCl] in the final solution = (1.0 × 10⁻⁵ mol) / (0.085 L) = 1.2 × 10⁻⁴ M
Molar concentration of Cl⁻ ions in the final solution = 1.2 × 10⁻⁴ M

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If you have learned Ksp, you will known that nthere is a small amount of Ag⁺ in the final solution due to slight dissociation of AgCl. Hence, the molar concentration of Ag⁺ in the final solution is NOT 0 M. It can be calculated as follows:

Refer to: https://cxp.cengage.com/contentservice/assets/owms01h/references/chemtables/gen_chem/ksp.html
Ksp for AgCl = 1.8 × 10⁻¹⁰
(The Ksp values from different sources may be slightly different.)

[Ag⁺] in the final solution
= Ksp / [Cl⁻]
= (1.8 × 10⁻¹⁰) / (1.2 × 10⁻⁴) M
= 1.5 × 10⁻⁶ M